1. Field of the Invention
This invention relates to lasers, and in particular to a method and apparatus for cooling a laser.
2. Description of the Related Art
Lasers and their components generate heat during operation, and so require cooling to prevent overheating and to extend the operational life of the laser. One known method of cooling a laser involves passing one or more streams of flowing air from a fan over the components.
Traditionally, sealed-off air-cooled gas lasers have used a split configuration with the laser source and a radio frequency (RF) power source separated into two assemblies connected by cables. In some prior art systems, each component employs its own cooling fan. In other lasers, users have been required to integrate laser components with separately provided cooling fans. For example, one laser introduced by the Synrad Corporation includes a sealed-off air cooled gas laser, marketed as the Series 48 models, which integrates a RF power source with a laser source by mounting the RF power source on the side of and along the entire length of the laser source. However, such Synrad lasers have not been supplied with cooling fans, but instead it was the responsibility of the user to obtain and integrate cooling fans with the laser, thus increasing costs and complexity in assembly.
In other lasers, at least one RF power source and at least one air cooling fan have been integrated with a laser source. For example, a method for cooling a gas laser is described in commonly-assigned U.S. Pat. No. 5,901,167, which is incorporated herein by reference and is made a part of the present application. In the U.S. Pat. No. 5,901,167, air flow from one or more fans 12 is split into two cooling air paths 14, 16, for example, illustrated by a prior art laser 10 shown in FIG. 1. Referring to FIG. 1, one path 14 provides flowing air to cool a RF power source which provides power to the laser source, and a second path 16 cools the laser source directly.
These paths may be designed to split the air flows in any desired ratio. For example, 50% of the flow may be split to a first path, and 50% to a second path; or alternatively 70% of the flow may be split to the first path, and 30% to the second path.
Methods known in the art for cooling lasers work well, but such methods include a number of drawbacks. For example, the splitting of the air flow between at least two components or into at least two paths provides less air flow to cool each of the components. In addition, the air flow, and therefore the cooling, is typically not symmetric, which causes undesirable deformations such as twisting or bowing of the laser source, thus causing optical misalignment of the laser source. For example, as shown in FIG. 1, air flow must turn about ninety degrees in order to travel through the fins of the laser source, and so more air tends to flow through the fins at the base of the laser source farthest from the fan than through the fins closer to the fan.
Furthermore, prior art lasers with such multiple air flows as shown in FIG. 1, for example, have an arrangement of components which does not lend itself to the most compact packaging. Accordingly, such lasers with cooling fans may be bulky.
Other known lasers with split air flow are described in U.S. Pat. No. 5,550,853 and also in commonly-assigned U.S. Pat. No. 5,894,493, which are incorporated herein by reference and are made a part of the present application.
We have invented a laser in which air flow from at least one fan cools a laser source and an RF power source in series, thus avoiding the disadvantages of splitting the air flow between such components.